package T4;

import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 马拉圈
 * Date: 2023-04-28
 * Time: 14:11
 */
public class Day34 {


    public static long[] arr;

    public static void getValues() {
        arr = new long[90];
        arr[0] = 1;
        arr[1] = 2;
        for (int i = 2; i < 90; i++) {
            arr[i] = arr[i - 1] + arr[i - 2];
        }
    }


    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        getValues();
        while(scanner.hasNextInt()) {
            int n = scanner.nextInt();
            System.out.println(arr[n - 1]);
        }
    }













    public static void main1(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNextInt()) {
            int n = scanner.nextInt();
            scanner.nextLine();
            StringBuilder stringBuilder = new StringBuilder();
            for (int i = 0; i < n; i++) {
                String str = scanner.nextLine();
                if(i >= 1) {
                    stringBuilder.append(", ");
                }
                if(str.contains(" ") || str.contains(",")) {
                    stringBuilder.append("\"");
                    stringBuilder.append(str);
                    stringBuilder.append("\"");
                }else {
                    stringBuilder.append(str);
                }
            }
            System.out.println(stringBuilder.toString());




        }
    }



}
